Switching converter

Abstract

To improve conversion efficiency at a DC-DC conversion time by providing driving units respectively for a plurality of switches and controlling the switches corresponding to a load current, an input voltage, an output voltage and an input/output voltage difference. When synchronously rectifying a plurality of first switches and a plurality of second switches by setting the first switches and the second switches alternately in an ON-state, the plurality of first switches are driven repeatedly in the ON- or OFF-state corresponding to a required output, the plurality of second switches are driven in the ON- or OFF-state in synchronization with the first switches, the driving of part of the plurality of first switches and part or all of the plurality of second switches is stopped corresponding to a load current value, an input voltage value, an output voltage value or an input/output voltage difference value.

1. A control circuit of a switching converter for converting an input electric power to an output electric power by setting a first switch and a plurality of second switches alternately to an ON-state, the control circuit including:
 a first driving unit driving the first switch; 
 a plurality of second driving units for respectively driving the plurality of second switches; and 
 a selection unit receiving a load current value and pulse width modulated signals from a comparator and stopping part or the whole of the plurality of second driving units based on said load current value. 
 
   
   
     2. A control circuit of a switching converter for converting an input electric power to an output electric power by setting a plurality of first switches and a plurality of second switches alternately to an ON-state, comprising:
 a plurality of first driving units driving respectively the plurality of first switches; 
 a plurality of second driving units driving respectively the plurality of second switches; and 
 a selection unit receiving a load current value and pulse width modulated signals from a comparator and stopping part of the plurality of first driving units, and part or all of the plurality of second driving units based on said load current value. 
 
   
   
     3. A switching converter including:
 a first switch; 
 a plurality of second switches; 
 a first driving unit driving the first switch; 
 a plurality of second driving units driving each of the plurality of second switches; 
 a detection unit detecting a load current value; and 
 a selection unit receiving said load current value and pulse width modulated signals from a comparator and stopping part or all of the plurality of second driving units based on said load current value. 
 
   
   
     4. A switching converter including:
 a plurality of first switches; 
 a plurality of second switches; 
 a plurality of first driving units driving each of the plurality of first switches; 
 a plurality of second driving units driving each of the plurality of second switches; 
 a detection unit detecting a load current value; and 
 a selection unit receiving said load current value and pulse width modulated signals from a comparator and stopping part of the plurality of first driving units and part or all of the plurality of second driving units based on said load current value. 
 
   
   
     5. An electronic device including a switching converter and a load operated by an output from the switching converter, the switching converter comprising:
 a first switch; 
 a plurality of second switches; 
 a first driving unit driving the first switch; 
 a plurality of second driving units driving respectively the plurality of second switches; 
 a detection unit detecting a load current value; and 
 a selection unit receiving said load current value and pulse width modulated signals from a comparator and stopping part or all of the plurality of second driving units based on a result of the detection of said load current value by the detection unit. 
 
   
   
     6. An electronic device including a switching converter and a load operated by an output from the switching converter, the switching converter comprising:
 a plurality of first switches; 
 a plurality of second switches; 
 a plurality of first driving units driving respectively the plurality of first switches; 
 a plurality of second driving units driving respectively the plurality of second switches; 
 a detection unit detecting a load current value; and 
 a selection unit receiving said load current value and pulse width modulated signals from a comparator and stopping part of the plurality of first driving units and part or all of the plurality of second driving units based on said load current value. 
 
   
   
     7. A switching circuit comprising:
 an A-coil connected to an output terminal; 
 a first A-switch switching electric power outputted via the A-coil; 
 a second A-switch rectifying the electric power to become direct current thereby the second A-switch becomes set to an ON-state alternately with the first A-switch; 
 an A-driving unit driving the first A-switch and the second A-switch alternately; 
 a B-coil connected in series to the A-coil; 
 a first B-switch switching the electric power outputted via the B-coil and the A-coil; and 
 a second B-switch rectifying the electric power to become direct current thereby the second B-switch becomes set to an ON-state alternately with the first B-switch, and 
 wherein the first A-switch and the second A-switch is set to have a larger capacity than the first B-switch and the second B-switch have, and 
 the selection unit drives the A-driving unit when an output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value. 
 
   
   
     8. A switching converter, comprising:
 an A-coil connected to an output terminal; 
 a first A-switch switching electric power outputted via the A-coil; 
 a second A-switch rectifying the electric power to become direct current thereby the second A-switch becomes set to an ON-state alternately with the first A-switch; 
 an A-driving unit driving the first A-switch and the second A-switch alternately; 
 a B-coil connected in series to the A-coil; 
 a first B-switch switching the electric power outputted via the B-coil and the A-coil; 
 a second B-switch rectifying the electric power to become direct current thereby the second B-switch becomes set to an ON-state alternately with the first B-switch; 
 a B-driving unit driving the first B-switch and the second B-switch alternately; and 
 a selection unit causing the A-driving unit and the B-driving unit to drive selectively, and 
 wherein the first A-switch and the second A-switch is set to have a larger capacity than the first B-switch and the second B-switch have, and 
 the selection unit drives the A-driving unit when an output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value. 
 
   
   
     9. A switching converter according to  claim 8 , wherein the A-coil may be set to have a larger capacity than the B-coil, and
 the selection unit drives the A-driving unit when the output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value. 
 
   
   
     10. A switching converter according to  claim 9 , wherein the A-coil has a lower inductance than the B-coil. 
   
   
     11. A switching converter according to  claim 8 , wherein the A-driving unit is set to have a larger capacity than the B-driving unit, and
 the selection unit drives the A-driving unit when the output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value. 
 
   
   
     12. A switching converter according to  claim 8 , wherein the A-coil extends from one terminal to a middle point thereof, and the B-coil extends from the middle point up to the other terminal thereof. 
   
   
     13. A switching converter according to  claim 8 , wherein the selection unit receives information representing an operating state of a load-sided circuit, and drives the A-driving unit or the B-driving unit in accordance with the information. 
   
   
     14. A switching converter according to  claim 8 , wherein the selection unit drives the A-driving unit or the B-driving unit in accordance with an output current. 
   
   
     15. A switching converter includes:
 a first A-FET having a drain terminal that is connected to an input terminal; 
 a second A-FET having a drain terminal that is connected to a source terminal of the first A-FET, and a source terminal that is connected to the ground; 
 an A-driving unit connected to gate terminals of the first A-FET and of the second A-FET, and driving the first A-FET and the second A-FET alternately; 
 an A-coil having one terminal that is connected to an A-oscillation part to which the source terminal of the first A-FET and the drain terminal of the second A-FET are connected, and having the other terminal that is connected to an output terminal; 
 a first B-FET having a drain terminal that is connected to an input terminal; 
 a second B-FET having a drain terminal that is connected to the source terminal of the first B-FET and a source terminal that is connected to the ground; 
 a B-driving unit connected to gate terminals of the first B-FET and of the second B-FET, and driving the first B-FET and the second B-FET alternately; 
 a B-coil having one terminal that is connected to an B-oscillation part to which the source terminal of the first B-FET and the drain terminal of the second B-FET are connected, and having the other terminal that is connected to A-oscillation part; and 
 a selection unit selectively driving the A-driving unit and the B-driving unit, 
 wherein the selection unit drives the A-driving unit when an output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value. 
 
   
   
     16. An electronic device having a switching converter and a load operating by an output from the switching converter, the switching converter including:
 an A-coil connected to an output terminal; 
 a first A-switch switching electric power outputted via the A-coil; 
 a second A-switch rectifying the electric power to become direct current thereby the second A-switch becomes set to an ON-state alternately with the first A-switch; 
 an A-driving unit driving the first A-switch and the second A-switch alternately; 
 a B-coil connected in series to the A-coil; 
 a first B-switch switching the electric power outputted via the B-coil and .the A-coil; 
 a second B-switch rectifying the electric power to become direct current thereby the second B-switch becomes set to an ON-state alternately with the first B-switch; 
 a B-driving unit driving the first B-switch and the second B-switch alternately; and 
 a selection unit causing the A-driving unit and the B-driving unit to drive selectively, 
 wherein the selection unit drives the A-driving unit when an output load is higher than a predetermined value and drives the B-driving unit when the output load is equal to or lower than the predetermined value.